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Posted: 7/24/2010 8:28:06 AM EDT
I am wiring up a new external service disconnect (200 Amp pass through with 8 breaker slots) and have a few questions.

For the ground wire, do you use the bus inside of the disconnect or the external lug that can be attached to the case?

There is going to be a GFCI plug wired up just under the panel with the wiring run inside of conduit.  When using conduit do you still have to clamp the wire or does the conduit suffice for this?
Link Posted: 7/24/2010 10:25:50 AM EDT
[#1]
IS this a main service for the house ? Do you have a ground rod ? is the conduit metal or plastic ? Many possibilites here, need more info.
Link Posted: 7/24/2010 8:01:27 PM EDT
[#2]
This service will be for a pole barn that is not built yet.  The service is going to be installed now since it will be late fall before work on the barn is started (power company increases the price by more then double for running equipment after the ground is frozen).

I have two 8' ground rods driven in six feet apart.  Now I have a length of number 6 solid copper wire that I am going to run from the ground rods to my box which is a Homeline 200 amp load center.  The box came with a lug that can be screwed to the back of the unit that the ground wire could be connected to.  My question is this  normally used or is the ground wire typically ran inside the box to the bus?

The conduit in question would be metal.  The offset between the meter and the service panel is metal and I was going to use metal conduit to the GFCI outlet too.

Here is an image to give an idea of what I am doing.
Link Posted: 7/24/2010 8:51:08 PM EDT
[#3]
Your grounds and neutrals will terminate on the same bus bar. Just make sure you bond the bus bar to the panel enclosure. You will need to run a ground wire to the GFCI. Don't use the conduit as your ground.

ETA- The panel should come with a green screw that screws through the bus bar into the panel or an offset piece of AL that terminates to the bus bar and screws to the panel.
Link Posted: 7/25/2010 8:28:12 AM EDT
[#4]
The new panel is a sub-panel and you can only use a 3-wire connection if there are NO other metallic connections between the buildings (like water line, phone lines, cable, etc.)
Link Posted: 7/25/2010 10:05:29 AM EDT
[#5]
Quoted:
The new panel is a sub-panel and you can only use a 3-wire connection if there are NO other metallic connections between the buildings (like water line, phone lines, cable, etc.)


If it is as shown above, it is not a sub panel.  It would be the first point of service, a sub panel would be after that panel.  
I believe OP is building a rack type service that is out in the open and free standing of any structures, similar to this 400 amp service for a pole barn:

The grounds and neutrals are bonded at this point, but not after.
Link Posted: 7/25/2010 12:16:00 PM EDT
[#6]
"If it is as shown above, it is not a sub panel. It would be the first point of service, a sub panel would be after that panel."

The drawing is not very clear.
Is the box on the left supposed to be a meter base?
Link Posted: 7/25/2010 2:16:12 PM EDT
[#7]
Quoted:
Quoted:
The new panel is a sub-panel and you can only use a 3-wire connection if there are NO other metallic connections between the buildings (like water line, phone lines, cable, etc.)


If it is as shown above, it is not a sub panel.  It would be the first point of service, a sub panel would be after that panel.  
I believe OP is building a rack type service that is out in the open and free standing of any structures, similar to this 400 amp service for a pole barn:
http://i2.photobucket.com/albums/y40/blue-nuts/WPSERVICE.jpg
The grounds and neutrals are bonded at this point, but not after.



This pic has totally nothing to do with op's original question. Basically ... Main panel's=  grounded to ground rod's and bonded to the neutral(via green screw or aluminum bus). In the case of a sub panel they want the ground and neutral to be from same origin as conductors ,not bonded at 2 different sources creating a differnce in potential.
Link Posted: 7/25/2010 3:07:45 PM EDT
[#8]
In the case of a sub panel they want the ground and neutral to be from same origin as conductors ,not bonded at 2 different sources creating a differnce in potential.


The problem of bonding neutral and ground in more than one place is that the grounding conductor now carries a portion of the current that should be confined to the neutral.

If the neutral ever becomes disconnected everything tied to the grounding conductor will riseto  the voltage drop in the grounding conductor, but no fault is present to open an OCD.
Link Posted: 7/25/2010 5:35:03 PM EDT
[#9]
Quoted:
Quoted:
Quoted:
The new panel is a sub-panel and you can only use a 3-wire connection if there are NO other metallic connections between the buildings (like water line, phone lines, cable, etc.)


If it is as shown above, it is not a sub panel.  It would be the first point of service, a sub panel would be after that panel.  
I believe OP is building a rack type service that is out in the open and free standing of any structures, similar to this 400 amp service for a pole barn:
http://i2.photobucket.com/albums/y40/blue-nuts/WPSERVICE.jpg
The grounds and neutrals are bonded at this point, but not after.



This pic has totally nothing to do with op's original question. Basically ... Main panel's=  grounded to ground rod's and bonded to the neutral(via green screw or aluminum bus). In the case of a sub panel they want the ground and neutral to be from same origin as conductors ,not bonded at 2 different sources creating a differnce in potential.


Looks similar to his picture though  You could have said this in your original post, but didn't...
Link Posted: 7/25/2010 5:43:58 PM EDT
[#10]
Quoted:
The drawing is not very clear.
Is the box on the left supposed to be a meter base?


Yes, the box on the left is the meter base.

So the general consensus is to run the #6 ground wire to the bus inside the box and not use the lug that mounts to the exterior of the box (the bonding screw was included with the box)?

My other question in regards to the conduit was not about using it as a ground, I just wanted to know if I had to clamp the NM or if the wire didn't need to be clamped if conduit was run from the service panel to the outlet box.  I have yet to find a knock out that will accept a piece of conduit and clamp the wire.
Link Posted: 7/25/2010 7:08:12 PM EDT
[#11]
Quoted:
Quoted:
The drawing is not very clear.
Is the box on the left supposed to be a meter base?


Yes, the box on the left is the meter base.

So the general consensus is to run the #6 ground wire to the bus inside the box and not use the lug that mounts to the exterior of the box (the bonding screw was included with the box)?

My other question in regards to the conduit was not about using it as a ground, I just wanted to know if I had to clamp the NM or if the wire didn't need to be clamped if conduit was run from the service panel to the outlet box.  I have yet to find a knock out that will accept a piece of conduit and clamp the wire.


Don't use NM in conduit. Get some thhn.
Link Posted: 7/26/2010 8:15:23 AM EDT
[#12]
Quoted:
Quoted:
Quoted:
The drawing is not very clear.
Is the box on the left supposed to be a meter base?


Yes, the box on the left is the meter base.

So the general consensus is to run the #6 ground wire to the bus inside the box and not use the lug that mounts to the exterior of the box (the bonding screw was included with the box)?

My other question in regards to the conduit was not about using it as a ground, I just wanted to know if I had to clamp the NM or if the wire didn't need to be clamped if conduit was run from the service panel to the outlet box.  I have yet to find a knock out that will accept a piece of conduit and clamp the wire.


Don't use NM in conduit. Get some thhn.


You should  not need a large conduit for a single GFCI receptacle, just 1/2 inch.

Just about every knockout will accept the conduit fitting for 1/2 inch EMT (what you are probbaly going to use, not rigid conduit).

Wires in conduit are not secured except for the devices they attach to.

Pretty hard to pull on a wire in any kind of conduit without opening something up.



Link Posted: 7/26/2010 8:41:37 PM EDT
[#13]
Quoted:
This service will be for a pole barn that is not built yet.  The service is going to be installed now since it will be late fall before work on the barn is started (power company increases the price by more then double for running equipment after the ground is frozen).

I have two 8' ground rods driven in six feet apart.  Now I have a length of number 6 solid copper wire that I am going to run from the ground rods to my box which is a Homeline 200 amp load center.  The box came with a lug that can be screwed to the back of the unit that the ground wire could be connected to.  My question is this  normally used or is the ground wire typically ran inside the box to the bus?

The conduit in question would be metal.  The offset between the meter and the service panel is metal and I was going to use metal conduit to the GFCI outlet too.

Here is an image to give an idea of what I am doing.
http://i104.photobucket.com/albums/m166/76239akm/Service.jpg



 If you intend on using a metal service conductors raceway nipple between the meter socket and the service equipment you need to bond the 2 enclosures with either bonding bushings or bonding locknuts, depending on if you expend the knockouts to their largest opening, and/or if the knockouts are concentric or eccentic

http://ecmweb.com/nec/code_qa/nec-code-quandaries-20100401/

As far as the branch circuit wiring and raceway to the GFCI, just strip the outer jacket off NMB and create single conductors. I'd pretty much follow the example photo w/ the 400A meter socket, pvc doesnt rust and I dont recall installing a 200A raintite panelboard w/ factory side KO's reducing down to 1/2" trade size
Link Posted: 7/27/2010 3:28:13 PM EDT
[#14]
Quoted:
Quoted:
Quoted:
Quoted:
The drawing is not very clear.
Is the box on the left supposed to be a meter base?


Yes, the box on the left is the meter base.

So the general consensus is to run the #6 ground wire to the bus inside the box and not use the lug that mounts to the exterior of the box (the bonding screw was included with the box)?

My other question in regards to the conduit was not about using it as a ground, I just wanted to know if I had to clamp the NM or if the wire didn't need to be clamped if conduit was run from the service panel to the outlet box.  I have yet to find a knock out that will accept a piece of conduit and clamp the wire.


Don't use NM in conduit. Get some thhn.


You should  not need a large conduit for a single GFCI receptacle, just 1/2 inch.

Just about every knockout will accept the conduit fitting for 1/2 inch EMT (what you are probbaly going to use, not rigid conduit).

Wires in conduit are not secured except for the devices they attach to.

Pretty hard to pull on a wire in any kind of conduit without opening something up.





A 1/2" KO is a 1/2" KO, EMT, IMC, or Rigid.  All end in 7/8" x 14 threads.  Also, if you're going to run in conduit, do yourself a favor and spend the extra bucks for THHN/THWN stranded.  Fuck solid wire.
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